ORIGINAL: otrcman
And not to gang up on you, Don, but have you ever considered the non-scale implications of attaching a rigid servo link to an all-movable rudder such as the DRI has ? On a real DRI there is no fixed fin, and the rudder is free to trail with the local slipstream regardless of how badly the airplane is sideslipping. The rudder contributes almost nothing to directional stability. Only the pilot's active effort keeps the airplane from sideslipping. When you attach a servo to the rudder on the model, the rudder is converted to a fixed (but controllable) fin. This change has a profound effect on how the scale model flies relative to the full scale airplane.
Another example of non-authentic scaling is rigidly attaching the elevator to a servo. On a real WWI plane the elevator is free floating and contributes very little to pitch stability. What we are doing by making the elevator rigid is effectively making the horizontal stabilizer far larger.
I don't mind at all...in fact, I love a good argument!
I'm not denying the "scaling effect." What I'm rejecting is making non-scale changes to our models, like increasing the size of the elevator or rudder, lengthening the nose, lowering the undercarriage, etc. that have nothing to do with making the model fly more like the original. These are changes that are done solely to make the model easier to fly. I also contend that for most WWI models a scale or near-scale airfoil will work just fine. This might not be true for a small scale P-51, but for most WWI models, scale EVERYTHING works fine.
I'm not sure I completely agree about the affect of attaching a servo. After all, on the real aircraft you've got a 150lb (or so) pilot with his boots constantly on the rudder bar. Maybe that's a little "mushier" and might be like adding springs to the forward end of the pull-pull cables. Remember also that the design rational behind the Fokker comma-shaped rudder wasn't just to "look cool" rather the portion ahead of the pivot line provided aerodynamic balancing just like the tips on the elevator halves (and the ailerons).